• The detailed design, build, and test of the drill heat string (DHS) is completed regarding the completion side of the core requirements within the project. All KPIs (torque rating, tension rating, and pressure rating) were reached.
• The full-scale test of the DHS was performed between October 2024 and January 2025 (approximately 4 months ahead of schedule) at the Ullrigg test centre of partner NORCE. The DHS manufactured in WP5 was installed, completed, and a thermal response test performed over 44 days. Difficulties with the assembly of the DHS were found to prevent the vacuum insulation to reach the KPI foreseen for this parameter (< 5 kPa), however this does not compromise the validation of the modelling work done in the project with the experimental data.
• The testing of the drill-in solution will be initiated when the activities related to it in WP5 are near completion.
• Three geothermal simulators, COMSOL (VITO), GWellFM (IFPEN) and GTW (IFE), were benchmarked for the same case studies. Models for fluid circulation in the flow pipes are developed and tested. A heat flow model for the closed loop system was developed and the design optimised. Finally, a validation of cylinder geometry-based simulation of the closed loop geothermal system was performed. The completed model for energy production on the HOCLOOP concept is prepared and validation is ongoing. The detailed information and conclusions of all work done is available in deliverables D2.1 to D2.5.
• The analysis of the data from the thermal response test on WP6 to validate the modelling work with the full-scale DHS test using water as the thermal fluid is ongoing. Preliminary results suggest no significant discrepancies between the model prediction and the observed.
• Complete and simplified models for the HOCLOOP concept using CO2 as thermal transport fluid have been almost fully developed. These models consider natural thermosyphon effect, assess the most suitable Equations of State, CFD refinement in some relevant points of the closed loop system, and compare the natural thermosyphon effect, heat transport and circulation between sCO2 based fluids and water.
• We reported in the first period report that the characterisation and data processing of the underground characteristics and surface energy systems of 4 European sites was completed and detailed in deliverable D4.1. A second edition of D4.1 was prepared presenting the same analysis for a Polish site (salt structures), following the extension of the scope of the HOCLOOP project by inclusion the University of Science and Technology of Krakow (AGH) as a new beneficiary through the Hop On facility.
• The input parameters, for each pilot site, are summarized and their “quality” evaluated. Simulation procedures (and the simulations) to define the static thermal and stress states at the pilot sites are performed. The conceptual closed loop system designed for each pilot is described together with the different scenarios to assess the long-term energy output of the conceptual systems.
• Capacity of CO2 and CO2 mixtures properties to match the requirements of different surface and sub surface conditions evaluated.
• Simulations of the underground HOCLOOP concept have been performed at 3 pilot sites in Italy, 1 in Poland, 1 in France, 1 in Germany and 1 in Belgium. They illustrate different geological contexts and various types of surface applications. The results of the simulations enable us to highlight the key parameters that influence the performance of the HOCLOOP geothermal solution.
• Stakeholder analysis has been implemented in two HOCLOOP pilot sites (Belgium and Poland). Local community acceptance has been analysed in Finland, Belgium and Germany. The community workshops (total 2) have included 34 participants and business model workshops (total 1) 21 participants.
• The environmental lifecycle assessment initiated the planning and definition of data to be collected for the life cycle inventory.
• An LCA integrated framework methodology for the HOCLOOP concept is defined.
